Gaucher disease is an autosomal recessive lysosomal storage disorder characterized by a deficiency in the lysosomal enzyme, glucocerebrosidase (GCB). GCB hydrolyzes the glycolipid glucocerebroside that is formed after degradation of glycosphingolipids in the membranes of white blood cells and red blood cells. The deficiency in this enzyme causes glucocerebroside to accumulate in large quantities in the lysosomes of phagocytic cells located in the liver, spleen and bone marrow of Gaucher patients. Accumulation of these molecules causes a range of clinical manifestations including splenomegaly, hepatomegaly, skeletal disorder, thrombocytopenia and anemia. (Beutler et al. Gaucher disease; In: The Metabolic and Molecular Bases of Inherited Disease (McGraw-Hill, Inc, New York, 1995) pp. 2625–2639)
Treatments for patients suffering from this disease include administration of analgesics for relief of bone pain, blood and platelet transfusions and, in some cases, splenectomy. Joint replacement is sometimes necessary for patients who experience bone erosion.
Enzyme replacement therapy with GCB has been used as a treatment for Gaucher disease. Current treatment of patients with Gaucher disease includes administration of a carbohydrate remodeled GCB derived from human placenta or Chinese hamster ovary (CHO) cells transfected with a GCB expression construct and known as alglucerase or imiglucerase, respectively. The treatment is extremely expensive in part because of the cost of removing sugars from GCB to expose the trimannosyl core of complex glycans in order to target the enzyme to mannose receptors on cells of reticuloendothelial origin. The scarcity of the human placental tissue (in the case of alglucerase), complex purification protocols, and the relatively large amounts of the carbohydrate remodeled GCB required all contribute to the cost of the treatment.